1. Field of the Invention
The present invention relates generally to the field of antennas, and more particularly to antenna systems for portable electronic devices.
2. Description of Related Art
An important attribute of portable electronic devices such as personal digital assistants ("PDA's") is ability to communicate with other electronic devices or systems. By such means PDA's can receive information from other systems, which can relieve a PDA user from a requirement to enter information in unit by unit using the conventional PDA screen input. Furthermore, by such means PDA's can send or relay collected and stored information to other systems, which can serve to make the PDA's "connected" branches of larger systems.
A number of different communication technologies have heretofore been incorporated into PDA's. One such technology is infrared beam technology. Via infrared beams, information can be passed between properly equipped, and closely situated, PDA's and computers. A second communication technology heretofore incorporated into PDA's is that used by conventional modems. PDA's have been made so as to include or incorporate modems and standard telephone line connection ports. Using the modems and ports, properly equipped PDA's have been able to send facsimile messages. A third communication technology that has been incorporated into PDA's is paging technology. PDA's, such as Apple's Newton MessagePad 110 and Motorola's Envoy, have been made capable of receiving wireless paging messages through an add-on accessory or by an internal transceiver.
Despite all of the advances made in communication capabilities of devices such as PDA's, it remains important and desirable to add new communication capabilities to such devices, and to further enhance the existent capabilities.
A communication network that has become firmly established in the United States and in various countries abroad over the past several years is the cellular communications network. The cellular communications network is a mobile telephone service that has a multitude of service areas (called "cells") that reuse transmission frequencies to increase the number of possible subscribers. Typically, each cell uses a different set of frequencies from those cells adjacent to it to prevent interference. Most commonly, service areas are divided into hexagonal cell sites that fit together to define a honeycomb. Each cell contains a transceiver that is connected to a central switch or mobile telephone exchange ("MTX") via a radio link. Each cell also contains a controller that controls the transfer of calls from one cell to another under the direction of the MTX. The MTX, in turn, is connected to the conventional telephone network so that calls from and to subscribers can travel at least partially over that network.
The cellular system offers communication capabilities that have not yet been fully exploited by portable electronic devices such as PDA's. It is, therefore, a shortcoming and deficiency of the prior art that there has not yet been developed a device especially well suited to combine the capabilities of PDA's and cellular telephones.